Is there a Cl- pump?

• Published in: The American journal of physiology Vol. 255; no. 5 Pt 2; p. R677
• Main Authors: Gerencser, G A, White, J F, Gradmann, D, Bonting, S L
• Format: Journal Article
• Language: English
• Published: United States 01.11.1988
• Subjects: Acetabularia - metabolism; Adenosine Triphosphatases - metabolism; Animals; Biological Transport, Active; Cell Membrane - metabolism; Chlorides - metabolism; Chlorides - pharmacology; Electrochemistry; Ion Channels - metabolism; Microsomes - metabolism; Mitochondria - metabolism; Models, Biological; Urodela
• ISSN: 0002-9513
• DOI: 10.1152/ajpregu.1988.255.5.R677

Three universally accepted mechanisms of Cl- transport across plasma membranes exist and they are 1) anion-coupled antiport, 2) cation-coupled symport, and 3) coupling to primary active ion transport through electrical and/or chemical processes. No unequivocal direct evidence has been provided for primary active Cl- transport (Cl- pump) despite numerous reports of cellular Cl- -stimulated adenosinetriphosphatase (ATPases) and of Cl- transport that cannot be accounted for by the three well-documented Cl- transport processes. It has been demonstrated that Cl- -stimulated ATPase activity is localized to both mitochondrial and microsomal aspects of the cellular apparatus. However, one group ascribes microsomal localization of Cl- -stimulated ATPase activity to mitochondrial contamination of that membrane fraction. Therefore, no Cl- pump could ever exist naturally in any plasma membrane. The other group simply states that there is plasma membrane localization of Cl- -stimulated ATPase activity that could function as a Cl- pump. Both arguments are logically advanced and their conclusions are consistent with their respective premises. Resolution to the question Is there a Cl- pump? rests with each reader's critique and objective evaluation.